linux-kernel - Re: [PATCH v2 0/3] led: ledtrig-transient: add support for hrtimer

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Date:   Wed, 13 Sep 2017 14:20:58 -0700
From:   David Lin <dtwlin@...gle.com>
To:     Pavel Machek <pavel@....cz>
Cc:     Jonathan Corbet <corbet@....net>, rpurdie@...ys.net,
        Jacek Anaszewski <jacek.anaszewski@...il.com>,
        hdegoede@...hat.com, Greg KH <gregkh@...uxfoundation.org>,
        robh@...nel.org, Rom Lemarchand <romlem@...gle.com>,
        linux-doc@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-leds@...r.kernel.org
Subject: Re: [PATCH v2 0/3] led: ledtrig-transient: add support for hrtimer

On Wed, Sep 13, 2017 at 1:20 PM, Pavel Machek <pavel@....cz> wrote:
>
> Hi!
>
> > These patch series add the LED_BRIGHTNESS_FAST flag support for
> > ledtrig-transient to use hrtimer so that platforms with high-resolution timer
> > support can have better accuracy in the trigger duration timing. The need for
> > this support is driven by the fact that Android has removed the timed_ouput [1]
> > and is now using led-trigger for handling vibrator control which requires the
> > timer to be accurate up to a millisecond. However, this flag support would also
> > allow hrtimer to co-exist with the ktimer without causing warning to the
> > existing drivers [2].
>
> NAK.
>
> LEDs do not need extra overhead, and vibrator control should not go
> through LED subsystem.
>
> Input subsystem includes support for vibrations and force
> feedback. Please use that instead.

I thought we are already over this discussion. As of now, the support
of vibrator through ledtrig is documented
(Documentation/leds/ledtrig-transient.txt) and there are users using
it.